This invention relates to scales having digital displays and operative within a coarse measuring range and a second smaller fine measuring range. The coarse measuring range lacks at least the least significant place of the fine measurement range. The invention further relates to such systems wherein means are provided for switching from one to the other of the measurement ranges.
In known scales of this type, the two ranges are provided in order to match the sensitivity of the scale to the weight of the load on the scale. The range switching in the known systems takes place manually, or automatically by means of a relay. All these known scales have a common feature, namely that both the coarse and the fine measurement range have the same zero point. In other words: when the total load on the scale has reached or exceeded a value corresponding to the predetermined fine range limiting weight, weighing can take place in the coarse measurement range only.
This limitation is often a considerable drawback. For example it may be a drawback when a successive weighing of a plurality of components of a mixture takes place or in the case of taring for a scale with subtractive tare (scales in which the range is reduced by the tare value) or for a combination of the two cases.